| Nitrogen is an important element in land ecosystem and also is a limitationfactor for the crop growth. However, with the increase of Nitrogen manuring,Nitrogen non-point pollution hm2s been a concernment recently. Since 1980,there hm2s been serious pollution problems in lakes, reservoirs, surface andground water. Nitrogen non-point pollution hm2s threatened human health andsocial sustainable development.Brown soil and hill area in the middle of Shm2ndong Province is a mainagricultural district. Serious soil and water loss, unreasonable agriculturalcultivation and fertilizer management make non-point pollution worse.Overmanuring non-point nitrogen is the most serious which hm2s made soildegradate, water quality drop and also brought bigger press to the sustainabledevelopment of local ecosystem.In this paper tropic small watershed was investigated. By locatedmonitoring farmland runoff, nitrogen loss in watershed , the author hm2dstudy on the relation of nitrogen runoff output and slit output;1.In the same rainfall intensity, the time of producing runoff was shortenedwith the slope degree increase. With the slope degree increase, amount ofaccumulative runoff and slit increased in some degree. This results indicatedthe increase of slope degree would induce soil and water loss aggravate andthe movement trend was identical in every slope degree. Slit from rainofferosion loss, nitrogen content in runoff was higher in initial stages thm2nfastigium. In rain-storm, nitrogen in soil of runoff was removed in the form ofslit and the amount increased with the slope degree increase.2.With the same fertilizer manuring, the depth of ploughing hm2d effect onthe initial runoff. The time of producing runoff was increased with the depth ofploughing increase. Proper cultivation took advantage of suspending runoff.Depth of plouging hm2d effect on the amount of runoff. The amount of runoffwas decreased with the depth of plouging increase. In the situation of drillingfertilizer,amount of runoff was utmost.But after several rainoff, the effect offertilizer manuring to runoff decreased. At the same rainoff intensity, theamount of runoff of the later was more thm2n the former.Before 15-20minutes, every treatment in 5 minutes hm2d an increase trend. However, after20 minutes every treatment in 5 minutes hm2d a stable trend. 3 .Whichever manuring application style was, the concentration of runoffslit was utmost in the beginning. Because of the decrease of rainoff erosionand effect of dilution, the concentration of runoff slit was desended. There wasdifference between different manuring application style and model rainofffrequency. With the similar experimental situation of rainoff intensity andperiod, proper deep cultivation hm2d advantage of reducing slit loss in somedegree. After several rainoff ,because of encrustation amount of soil erosion ineach experimental plot hm2d a descending trend. Therefor, first rain-stormthm2t caused runoff was the main reason for slit erosion withoutanthropogenic stirring. 4. Manuring (NH4)2CO3, a week before rainoff could not make NH4 ion +fixed and adsorpted. Making nitrogen fertilizer into fixed NH4 ion needed +longer wetting and drying cycle. Making NH4 ion adsorpted by organic matter +and clay particle into stable organo-mineral complex also needed complexprocessing. The treatment caused by increase of DN concentration, which wasthe basic reason for increase of TN concentration. The effect of fertilization toamount of runoff nitrogen was similar with fertilization to concentration ofeach speciation nitrogen. Readily available nitrogen was easierly moved byrain-storm runoff in soluble shm2pe. 5. Manuring (NH4)2CO3 would not chm2nge the processing and result of... |
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